Counterweight



A. sw-ANSON coUNTERwE'IGHT Sept. 3, 1940.

Filed O Cb. 27, 1939 Patented Sept. 3, 1940 amsn coUNrEnWEiGHT Arthur Swanson, Pampa, Tex., assigner to' Cabot Shops, Enc., Boston, Massachusetts Mass., a corporation of Application October 27, 1939, Serial No. 301,610

3 Claims.

My invention relates to pumping rigs of the type commonly used in oil fields, and consists primarily in an improved counterweight construction or mechanism by means of which the crank arms of a pumping rig may be adjustably counterbalanced to compensate for the weight of the sucker rod suspended from the walking beam and thus make for a smoothly-operating, efcient rig. Y l.

The most important objects of my invention are to provide a counterweight which can easily be attached to and removed from a crank arm and which may be manufactured at a cost lower than has heretofore been found practicable.

The counterweight mechanism of my invention includes an improved yoke provided with gripping lugs on the inner faces of the yoke pieces and means for detachably supporting one or more weights. The gripping lugs render it unnecessary to machine the yoke pieces to t the surface of the crank arm.

A feature of the invention is in the novel shape and arrangement of the parts wherein the weight helps to clamp the'yoke to the crank arm and g5 the yoke helps the crank arm to grip its shaft.

These and other objects and features of my invention will be more readily understood and appreciated from the following detailed description of a preferred embodiment thereof selected for purposes of illustration and shown in the accompanying drawing, in which:

Fig. l is a view in side elevation of a pumping rig provided with counterweights constructed according to my invention,

Fig. 2 is a view partly in elevation and partly in section of a crank arm and associated weights.

Fig. 3 is a view in cross section along the line 3 3 of Fig. 2,

Fig. e is a plan View of one of the weights,

Fig. 5 is a view in elevation of the weight,

Fig. 6 is a bottom plan View of the weight,

Fig. 7 is a View in elevation of the inside face of the yoke to which the weights are secured, and

45 Fig. 8 is a View in elevation ofthe outside face of the yoke.

The general arrangement of the pumping rig shown in the drawing is conventional and comprises a frame iii of steel beams supported above 50 the ground on a concrete foundation Il. Supported by the frame iii is a gear box l2 in which is journalled a shaft I3. The shaft I3 may be rotated from any convenient source of power. At one end of the frame l0 is a pyramidal Sampson frame i4 of steel or other suitable material to the (Ci. 'i4-591) top of which is bolted a saddle bearing I5 on which an elongated walking beam l' is arranged to rock. One end of the walking beam i6 overhangs the ground and carries a -conventional Y mule head il to which are secured cables I8 by means of which the suckerrod is coupled to the Walking beam Secured to the walking beam i@ over the sha:c+ it is a transverse shaft 2li to the ends of which is secured a pair of pitman arms 22 (only one of which is apparent in the 'lo drawing). The lowerrend of each pitman 22 is pivotally ccnnected'to a crank arm 23 by means of a pivot pin 25. The construction thusfar described is all well known commercial equipment and forms no part of my invention.

One end of the crank arm 23 is bored and split to form a pair of spaced clamping lugs 2d and a bore into which the shaft i3 extends. A key EQ prevents relative rotation of the crank and the shaft i3. A pair of yoke pieces 28 is secured to the crank arm 23 as shown in the drawing. Each yoke piece 25 is provided with a lug 23 on its inner face near its lower end and ears are formed at the ends of the yoke pieces and bored transversely to receive a bolt. The upper ends of the yoke pieces 26 are secured to the lugs 2i by means of a transverse bolt 27, and it will be apparent that when the bolt 27 is tightened the ears on the end of the yoke pieces 26 will force the lugs 2d of the crank arm together, thus gripping the shaft I3 very tightly. The yoke pieces are so shaped that they do not bear on the crank 23 except at the lugs 2li and 28. This design is of importance inasmuch as it means that the yoke pieces do not have to be carefully machined to fit the crank arm 23, an expensive undertaking. The lower ends of the yoke pieces 2t are held together by another transverse bolt 3l).

The lower faces of the yoke pieces 26 are curved to form a continuous downwardly convex 40 arc and are provided with means for supporting curved weights 32 and 34 below the yoke 2t. Since it is convenient to provide for adjustment, I provide a variety of small interweights 32 and a larger master weight 34. Each shimlike interweight 32 is recessed on its upper surface as shown at 33 to receive the head of the bolt 3|] and the corresponding nut, and the master Weight 3Q is also recessed as shown at 36.

Vertical holes are provided in the yoke pieces 26 and in the interweights 32 and the master weight 34. A pair of rectangular apertures 3i are formed in the bottom of the master weight 34 and in register with the vertical holes. Bolts 38 are inserted from below through the master 55 weight 34, the interweights 32, and the yoke pieces 26, and nuts 39 are arranged to tighten the bolts 38 to draw the master weight and interweights against the lower surfaces of the yoke pieces 26. The heads of the bolts 38 fit into the apertures 31 and are thereby7 held against rotation. It will be apparent that when the inter- Weight and the master Weight are drawn tightly against the convex lower surfaces of the yoke pieces 26, the yoke pieces 26 are pressed against the crank arm 23. That is to say, the interweights and the master weight resist any tendency on the part of the yoke pieces 26 to open out or loosen.

It will be apparent from the drawing and from the foregoing description that I can use the master weight 34 by itself or in combination with any desired number of smaller interweights or shiins 32. For a relatively shallow well the master weight 34 by itself may be sufcient to counterbalance the weight of the sucker rods, but when the rig is to be used on a deep Well, it will be found necessary to add additional weights in order to obtain compensation for the increased weight of the sucker rods. 'I'he construction of the yoke pieces 26 and the weights 32 and 34 is such that very little machining is necessary and the counterbalancing equipment of my invention is much cheaper to manufacture and convenient to install than any heretofore used in the oil fields.

Having now described and illustrated my invention what I claim is new and desire to secure by Letters Patent of the United is:

1. A counterbalanced pumping rig, which coniprises a crankarm, a pair of spaced lugs disposed at one end of said crank arm, a pair of yoke pieces, a bolt joining the yoke pieces at one end and passing through the lugs on the crank arm, a lug on the inner face of each yoke piece, a bolt joining the other ends of the yoke pieces and causing the lugs thereon to grip the crank arm, a counterweight, and means securing the counterweight to the yoke pieces.

2. In a pumping rig including a shaft, a crank arm bored and split at one end to form a pair of spaced lugs having curved opposed surfaces Aproviding an aperture for said shaft, a pair of yoke pieces, al bolt passing through one end of the yoke pieces and through the lugs on the crank arm to tighten the lugs around the shaft and secure the yoke pieces to the crank arm, and a counterweight secured to the yoke pieces.

3. In a pumping rig including a shaft, a crank arm shaped at one end to form a pair of lugs having curved opposed surfaces providing an aperture for said shaft, a pair of yoke pieces having arcuate lower faces, a bolt passing through the upper ends of the yoke pieces and through the lugs on the crank arm to tighten the lugs around the shaft and secure the yoke pieces to the crank arm, a weight having a curved upper surface f1tting the bottom faces of the yoke pieces, and

bolts drawing the weight against the yoke pieces f and thereby forcing the yoke pieces to grip the crank arm.

ARTHUR SWANSON. 

